In construction, modular panel systems are commonly used to reduce build cost and construction time. Modular panel systems typically allow for the rapid construction of floors, walls and ceilings, albeit often at the compromise of reduced aesthetic appearance. A prime example of such a modular panel system is a suspended ceiling, which can be found in most professional environments, such as for example office spaces. A suspended ceiling typically comprises a metal or plastic grid defining rectangular or square recesses, which are filled with tiles to form a continuous ceiling.
In such modular systems, e.g. a suspended ceiling, lighting may be integrated into the system, typically by replacing one or more tiles with a lighting unit such as a luminaire. Most suspended ceilings comprise luminaires in which a number of fluorescent light tubes are present. For a number of reasons, such luminaires are not ideal. Firstly, such luminaires are considered aesthetically displeasing, i.e. obtrusive. Secondly, in order to improve light efficiency from such luminaires, they usually contain a reflector, which commonly has a parabolic shape. This however can cause glare for an occupant of the office space if the reflected light exits the luminaire under shallow angles to the plane of the modular system. Glare can be very disturbing in an office environment, as it can obscure the image on a computer monitor and can cause physical discomfort, e.g. headaches or sight problems, to the occupant when being subjected to the glare for a prolonged period of time. This is why health and safety standards such as the IEC60598-1:2008 standard in Europe require lighting solutions to comply with stringent requirements for preventing excessive glare levels.
Solutions exist to overcome glare. A straightforward solution is shown in FIG. 1, in which a suspended ceiling luminaire 10 is shown. The luminaire 10 comprises a plurality of chambers defined by respective parabolic reflectors 12, with a fluorescent light tube 14 fitted in each of the chambers. Each light tube 14 is offset from the light exit plane 10a of the luminaire 10 by a distance d such that light emitted by the fluorescent light tube 14 under a shallow angle is reflected by the parabolic reflector 12, as indicated by the dotted broken arrow. This increases the exit angle of the light, thus reducing glare. A drawback is that this solution leads to relatively bulky luminaires, which can be considered aesthetically unsatisfactory.
Another solution is shown in FIG. 2, in which a luminaire 10 for integration in a suspended ceiling is fitted with a micro-lens optical plate or diffuser 20, which has the function of preventing shallow angle light beams from exiting the luminaire 10. As this causes a substantial amount of light being reflected back into the chamber 11 of the luminaire 10, the luminaire 10 may comprise a reflector 22 to recycle such reflected light. Commonly, the micro-lens optical plate takes the form of a prism plate.
The company SwitchMade offer a light emitting diode based (LED) luminaire marketed under the name Paneos® for integration in a suspended ceiling. This has the advantage of lower energy consumption compared to fluorescent light tube-based luminaires. However, as these luminaires replace tiles in the ceiling, they still disrupt the visual appearance of the suspended ceiling.
The Gemino Company (www.gemino.it) markets a suspended ceiling solution in which the light fittings can be integrated into the band raster of the ceiling. The band raster consists of the main structural beams of the suspended ceiling. With smaller form factor lighting such as LED lighting this is a feasible solution, and has the advantage of the improved appearance of the ceiling due to the fact that no tiles need replacing with luminaires. This however increases the manufacturing complexity of the band raster, and thus the cost of the overall design. Moreover, this solution is unsuitable for retrofitting purposes, and is difficult to maintain as the band raster cannot be easily disassembled for maintenance purposes.